Incubation Team
Shell density of planktic foraminifera
These are the X-ray CT (Computer Tomography) images representing shell density of planktic foraminifera (marine zooplankton with carbonate skeleton) which were collected from different water depths by the sediment trap deployed at Stn. K2 (47°N, 160°E) in the North Pacific (left: computed images of surface texture of shells, center: cross section images of shells representing shell density, right: colored image of distribution of shell density).
In the North Pacific at present, carbonate saturation horizon locates shallower than 150 m water depth, therefore carbonate shells that were precipitated by phyto- and zooplankton are dissolved below this water depth (when the value of carbonate saturation index (Ω) is above 1.0, carbonate shells are preserved; when Ω is below 1.0, carbonate shells are dissolved.) X-ray CT images of specimens captured from 150 m water depth (upper figures) show thick and higher density (red colored) of the walls and indicate good preservation of carbonate shell. On the contrary, the specimens from 1,000 m water depth (lower figures) show thinner and lower density of walls (yellow to blue colored) and indicate damaged carbonate shells.
The X-ray CT method to know the carbonate preservation states in the water column has great advantages for monitoring marine ecology and chemistry, related to the ocean acidification.
Provided by :
Katsunori Kimoto, Masahide Wakita
Research Institute for Global Change (RIGC), JAMSTEC
THE TOHOKU UNIVERSITY MUSEUM
